The Tatarstan Airlines plane was trying to make a second landing attempt when it touched the surface of the runway near the control tower, and was "destroyed and caught fire," said Sergei Izvolky, the spokesman for the Russian aviation agency.
The Emergencies Ministry said there were 44 passengers and six crew members aboard the evening flight from Moscow and all had been killed. Kazan, a city of about 1.1 million and the capital of the Tatarstan republic, is about 720 kilometers (450 miles) east of the capital.
The ministry released a list of the dead, which included Irek Minnikhanov, the son of Tatarstan's governor, and Alexander Antonov, who headed the Tatarstan branch of the Federal Security Service, the main successor agency to the Soviet-era KGB.
Some Russian air crashes have been blamed on the use of aging aircraft, but industry experts point to a number of other problems, including poor crew training, crumbling airports, lax government controls and widespread neglect of safety in the pursuit of profits.
The Emergencies Ministry released photographs from the nighttime scene showing parts of the aircraft and debris scattered across the ground. Ambulances lined up in front of the airplane building.
It was not clear why the plane's first landing attempt was unsuccessful. Boeing said it would provide assistance to the investigation into the cause.
"Boeing's thoughts are with those affected by the crash," the company said in a statement on its website.
A journalist who said she had flown on the same aircraft from Kazan to Moscow's Domodedovo airport earlier in the day told Channel One state television that the landing in Moscow had been frightening because of a strong vibration during the final minutes of the flight.
"When we were landing it was not clear whether there was a strong wind, although in Moscow the weather was fine, or some kind of technical trouble or problem with the flight," said Lenara Kashafutdinova. "We were blown in different directions, the plane was tossed around. The man sitting next to me was white as a sheet."
Tatarstan is one of the wealthier regions of Russia because of its large deposits of oil. It is also is a major manufacturing center, producing trucks, helicopters and planes. About half of the people who live in the republic are ethnic Tatars, most of whom are Muslims.
Russia's last fatal airliner crash was in December, when a Russian-made Tupolev belonging to Red Wings airline careered off the runway at Moscow's Vnukovo airport, rolled across a snowy field and slammed into the slope of a nearby highway, breaking into pieces and catching fire. Investigators say equipment failure caused the crash, which killed five people.
A 2011 crash in Yaroslavl that killed 44 people including a professional hockey team was blamed on pilot error. And Russian investigators found that the pilots in two crashes that killed 10 and 47 people in recent years were intoxicated.
Associated Press writer Lynn Berry contributed to this report.